Grid-controlled gas or vapor-filled discharge vessel for high operating voltages



s w T 'June 17, 1941. 2,245,998

GRID-CONTROLLED R VAPOR-FILLED DISCHARGE VESSEL ,FOR HIGH OPERATINGVOLTAGES INVENTOR HE/EBf/FT F/f/IFC 24x91 mm ATTORNEY Patented June 17,1941 TENT oFF cs- GRID-CONTROLLED GAS R VAPOR-FILLED DISCHARGE VESSELFOR HIGH OPERAT- ING VOLTAGES Herbert Pietsch, Berlin-Siemensstadt,Germany,

assignor to Fides Gesellschaft fiir die Verwaltung und Verwertung vongewerblichen Schutzrechten mit beschrankter Haftung, Berlin, Germany, acorporation of Germany Application June 28, 1939, Serial No. 281,577 InGermany July 15, 1938 2 Claims.

The invention relates to a gaseous discharge device and especially agrid-controlled gaseous discharge device.

An object of the invention is to prevent the occurrence of any dischargebetween the anode and cathode outside of the space occupied by the gridelectrode.

Another object is to provide blocking discharge rneans between thecontrol electrode and the container wall that will not readily conductheat to the container wall.

Other objects and advantages of the invention will be apparent from thefollowing description and drawing, in which the figure is a view, mainlyin cross-section, of a'discharge device illustrating a preferredembodiment of the invention.

In gaseous discharge devices, the cathode and anode are spaced from oneanother with generally a grid in the space between the two. Itoccasionally happens, however, that because of the ionization of thegaseous atmosphere, a discharge may occasionally find an easy path fromthe cathode around the side of the control electrode to the anode. Theseoccasional discharges will, of course. cause trouble because theoccurrence will be at a time when the grid is supposed to prevent thebreakdown of the tube. The main purpose of the invention is to preventsuch a discharge occurring.

A large proportion of the discharge devices that are utilized forindustrial control have glass walls. The control grids in such dischargedevices that are being actively and frequently utilized, will generallyhave a high temperature because of the heat of the discharge. It isanother object of my invention that the means preventing dischargesaround the control electrodes will not directly and rapidly transfer theheat of the control electrode in operation to the glass wall of thecontainer and damage it.

In the figure is disclosed a typical gaseous discharge device used forcontrol purposes. This device in its specific form, is to be taken forpurposes of illustration and notin a limiting sense. The device includesa cathode I that is preferably of the so-called hot type, eitherdirectly or indirectly heated.

Th anode 2 may be of any desired shape. The control electrode 3 isillustrated as having preferably an H-shaped cross-section with thecathode l illustrated in the lower portion of the H and the anode 2projecting into the upper portion of the H, and a perforated centralpartition 4 for the passage of the discharge therethrough under thecontrol of the grid. The control grid i preferably supported by the wire5 fastened in the press, which also supports the cathode. The glassvessel or container 6 has preferably a constriction 1 for providing anarrow circular gap between the control electrode 3 and the vessel Wall6. This constriction is preferably at the upper portion of the tube 'asillustrated, although it may be located at other places in the device. Aring 8 is utilized toblock the space between the control electrode 3 andthe container wall 6. This ring is preferably held by a U-shaped metalring 9, fastened to the control grid 3.

This ring 8 is preferably of flexible material, having a low thermalconductivity. In order to obtain suflicient high thermal resistance,thin foils or metal of low thermal conductivity may be used. Of thenon-metallic materials, mica is especially adapted for use as a ring, inview of its high thermal resistance. The ring, if constructed of mica orother non-conducting material, may be provided with a conductingcoating, as for example, a graphite coating. This conductive coating mayonly cover the zone of the flexible ring which is in contact with theglass wall, or the entire surface of the flexible ring may be madeconductive with such a coating. The coating is generally in the form ofa thin film on the mica. This conductive coating will prevent chargesaccumulating on the glass or mica, and will also aid in preventing anydischarge not under the influence of the control electrode. The graphitecoating is designated by the numeral l 0 on the drawing.

If the field of the anode terminates in the region of the flexible ring,it is advisable that the ring have no sharp edges or points which wouldcreate field emission. If wire gauze is used for the circular gapbetween the vessel wall and the control part, then this gauze should bescreened adequately at the position opposite the anode by the controlbody.

When flexible mica is utilized for the ring, the mica will absorb orcushion any jolts or jars given to the outer casing and will preventthetransfer of such shocks to the inner electrodes. If the ring weremade of any unyielding material, such as glass, these shocks would betransmitted or, if the glass were thin, the glass would crack.

Although I have shown and described a specific embodiment of myinvention, I do not desire to be limited thereto, as various othermodifications of the same may be made without departing from the spiritand scope of the appended claims.

I claim:

a thin layer of electrical conducting material thereon.

2. A gaseous discharge device comprising a container, a cylindricalcontrol electrode therein 1. A gaseous discharge device comprising a 5having a perforated partition therein, an anode container, a cylindricalcontrol electrode therein having a perforated partition therein, ananode on one side of said partition, a cathode on the other side of saidpartition, and a flexible ring of low thermal conductivity attached tothe outer portion of said control electrode and extending to the wall ofsaid container, said ring having on one side of said partition, acathode on the other side of said partition and a flexible ring of micaattached to the outer portion of said control electrode and extending tothe wall of said container, said ring having a thin layer of electricalconducting material thereon.

HERBERT PIETSCH.

